«In Norway,» I wrote in these pages on July 25, «to speak negatively about any aspect of the Muslim faith has always been a touchy matter . . . . It will, I fear, be a great deal more difficult to broach these issues now that this murderous madman has become the poster boy for the criticism of Islam.»

This statement was harshly criticized by Norway’s multicultural left. How dare anyone speak of such issues at a time like this! It was as if the concerns I had raised were abstract or narrowly political.

On the contrary, Islam’s rise in the West is a subject that needs to be discussed frankly, without euphemism or disinformation. The survival of secular democracy, individual liberty and women’s rights depends upon it.

Sadly, my prediction turned out to be far more prescient than I could have imagined. In the weeks and months following Breivik’s rampage, dozens of high-profile Norwegian leftists stepped forward to claim that critics of Islam shared responsibility for his crimes—and to call, darkly if vaguely, for action.

On July 28, for instance, novelist Jostein Gaarder, author of «Sophie’s World,» and social anthropologist Thomas Hylland Eriksen, writing in the New York Times, linked Breivik to «right-wing» Islam critics, including me. «Mr. Breivik,» they wrote, «has now shown that those who claim to protect the next generation of Norwegians against Islamist extremism are, in fact, the greater menace.»

Lars Gule, former head of the Norwegian Humanist Association, agreed. «It is obvious,» wrote Mr. Gule in VG, Norway’s largest daily, on Aug. 1, «that certain groups, persons, and communities have contributed to Breivik’s warped view of reality, and these people need to take a good look at themselves. If not, others must help them.»

On Aug. 22, Norway’s newspaper of record, Aftenposten, ran an op-ed coauthored by Mr. Eriksen and three others—social anthropologist Sindre Bangstad, philosopher Arne Johan Vetlesen and Bushra Ishaq of Norway’s Anti-Racist Center. Titled «Hateful Utterances,» it called for tighter limits on free speech in the wake of July 22.

«Certain hateful utterances,» the authors insisted, «are legally and morally unacceptable.» Rejecting «free speech absolutism,» and criticizing the United States for «go[ing] the furthest in protecting the right to expression—including hateful expression,» they argued that «Norwegian editors as well as politicians» needed to make it clear that «it is not a human right to express oneself in public; and that certain hateful utterances . . . are not acceptable.»

Anthropologist Runar Døving agreed, declaring flatly, in a Sept. 2 interview with the Norwegian weekly Morgenbladet, that criticism of Islam should be censored. Mr. Døving admitted that his view of the public square was «authoritarian»—the expression of certain ideas, he said, should simply not be allowed—and that he was «entirely in favor of what many people are now describing as a witch hunt,» because «there needs to be an investigation of what was written before July 22» so that we can «see the connection between words and actions.»

Indeed, a witch hunt is under way in Norway. In the name of multicultural tolerance and social harmony, some of the most powerful members of the country’s left-wing intelligentsia are seeking to silence Islam’s critics by linking them to a mass murderer who has become the most despised individual in modern Norwegian history. This campaign has been carried out on a scale, and with an intensity, that is profoundly unsettling. It should be firmly resisted by everyone who treasures freedom of expression and recognizes it as the cornerstone of human liberty.